1. Field of the Invention
The present invention relates to an information processing apparatus having a display unit for displaying information to the user, such as a personal computer, and more particularly to an information processing apparatus where the screen saver displayed on the display unit is executed without interrupting the power saving function, a terminal control program and a screen saver program for executing the screen saver without interrupting the power saving function, and a terminal control method for preventing a burn-in of the display unit without interrupting the power saving function.
2. Description of the Related Art
In many information processing apparatuses, such as personal computers (hereafter called PC), portable telephones and PDAs (Personal Digital Assistants), it is set such that a screen saver program, for displaying images (still pictures, moving pictures) on a display unit when operation by the user is not performed for a predetermined period (screen saver activation period), is activated so as to prevent a burn-in of the display unit, such as a CRT (Cathode Ray Tube) connected to the information processing apparatus. Operation by the user is, for example, key input from the keyboard, input by moving or clicking the mouse, and pressing the power supply button.
Initially a screen saver was for protecting the display unit and was not created with concern for the user, so a relatively simple visual effect (e.g. a logo was displayed at various locations on the screen at a time interval) was displayed on the display unit. Recently, however, screen savers for displaying more elaborate visual effects that attract the interest of the user are seen on the market. Actually such screen saver programs having more elaborate visual effects tend to attract users even more. But for the processing of such screen savers with elaborate visual effects, a complicated operation, such as image processing requiring high computing amount, is required and more resources, such as a CPU (Central Processing Unit), memory and hard disk, are required, and as a result, the load on the information processing apparatus increases.
On the other hand, in information processing apparatuses, when operation by the user is not performed for a predetermined time (standby shift period), the program shifts to standby mode where power consumption is lower, so as to acquire authentication conforming to the power saving standard specified by the standards organization. In standby mode, the setup information is saved in the memory, and power is supplied only to areas required for saving the setup information. When the operation by the user is performed, the setup information is read from the memory, and the information processing apparatus is returned to and controlled to be the operating status before standby mode.
Even if a shift to standby mode is set, the information processing apparatus does not shift to standby mode while executing a processing which requires high load on the information processing apparatus (e.g. processing consuming considerable CPU time) via the OS (Operating System). This is because of preventing the interruption of important processing for the user, such as technology computation being executed in the background by shifting to standby mode by mistake. Recently some screen savers impose loads onto the system higher than the level which stops the information processing apparatus from shifting to standby mode because of the visual effects thereof, so if the load of the screen saver that the user sets is high, the system does not shift to standby mode at all.
To prevent this situation (as a work around), the information processing apparatus does not perform the processing of the screen saver, if the display unit is cleared (e.g. power of the liquid crystal display is OFF/standby separately from the PC main body) to decrease the load on the information processing apparatus. So if the user do not operate for a predetermined period (screen clear period), the information processing apparatus turns OFF the power supply of the display unit so as to prompt a shift to standby mode.
As a technology related to screen savers and power saving functions, it is proposed that if the operation not necessary to be displayed on the display device (e.g. operation of playback or fast forward button of the CD player function) is executed in standby mode by the user, the power saving status of the display device is maintained (Japanese Patent Application Laid-Open No. 2002-73225), and it is proposed to further decrease power consumption by intermittently supplying the power to one means which can automatically detect a return signal after synchronization signals are not longer detected in the display device (Japanese Patent Application Laid-Open NO. 2003-76352). It is also proposed that in the display of a mobile communication terminal, when standby mode where the screen saver is executed shifts to partial mode where the screen saver ends, if the display content of the conventional display does not change very much during the shift, the ratio of the screen saver image in the entire display is gradually decreased in steps to impress the user changing (Japanese Patent Application Laid-Open No. 2001-186040), and it is also proposed that after the screen saver is executed, the display is turned OFF and the display of the screen saver disappears if an electronic mail does not arrive for a predetermined time after the execution of the screen saver (Japanese Patent No. 3220015).